docs: def initialize(self, prefix_name='default', *args, **kwargs):
          """
          Initializes a workdir by adding a new prefix to the workdir.
  
          Args:
              prefix_name(str): Name of the new prefix to add
              *args: args to pass along to the prefix constructor
              *kwargs: kwargs to pass along to the prefix constructor
  
          Returns:
              The newly created prefix
  
          Raises:
              PrefixAlreadyExists: if the prefix name already exists in the
                  workdir
          """
          if self.loaded:
              raise WorkdirError('Workdir %s already initialized' % self.path)
  
          if not os.path.exists(self.path):
              LOGGER.debug('Creating workdir %s', self.path)
              os.makedirs(self.path)
  
          self.prefixes[prefix_name] = self.prefix_class(
              self.join(prefix_name), *args, **kwargs
          )
          self.prefixes[prefix_name].initialize()
          if self.current is None:
              self._set_current(prefix_name)
  
          self.load()
  
          return self.prefixes[prefix_name]